Print version ISSN 0100-8358
OCHOA, M. C; CHAILA, S and SOBRERO, M. T. The space aggressiveness index (SAI) for the Chenopodium album in cotton crop in santiago del estero, Argentina. Planta daninha [online]. 2011, vol.29, n.3, pp.481-487. ISSN 0100-8358. http://dx.doi.org/10.1590/S0100-83582011000300002.
The Space Aggressiveness Index (SAI) is a bio-ecological parameter that depicts weed distribution characteristics. There are not antecedents about this subject in cotton crop. This paper was aimed at determining the space aggressiveness index for Chenopodium album (CHEAL) and relating it to yield losses. Work was done on the Guazuncho-INTA cultivar throughout the 2007-2008 campaign in La Maria Experimental Field, EEA INTA Santiago del Estero. To compute the space aggressiveness index a model that includes the outstanding height, dry biomass, and infected area of the individual plant together with the quantity, dry biomass and average height of the offspring was used. The 200 sq m cropland was divided into ten plots and parametric statistical analyses, ANOVA, and Tukey test (0,05) were made. As to the the results obtained were: a) Cotton: -average weight per plot: 105.000 g; -weight per plant: 597 g; total number of plants: 79,30; average height: 0,59 m; average yield: 2,592 kg ha 1 and, b) CHEAL: weight per plot: 4,290 g; average number of individuals per plot: 18,7; average height: 2,72 m; parent plant height: 3,45 m whereas for the offspring the figures were: 187 individuals; average height: 2,40 m; average dry matter: 58 g in plot of surpassing plant. Cotton yield was 2,329,50 kg ha-1 and crop losses were of 89,76%. The space aggressiveness index obtained was that of 3,76 (i.e. low-intermediate). Such an index indicates that numerous plants growing around a main weed act together in distribution. The lower space aggressiveness index, the higher yield losses occur in cotton crop.
Keywords : CHEAL; distribution; model; weed; yield.